Most of the energy used in the world today is derived from the combustion of carbon and hydrogen containing fuels such as coal, oil and natural gas. In addition to carbon and hydrogen, these fuels contain oxygen, moisture and contaminants such as ash, sulfur, nitrogen compounds, chlorine, mercury and other trace elements. Awareness to the damaging effects of the contaminants released during combustion triggers the enforcement of ever more stringent limits on emissions from power plants, refineries and other industrial processes. There is an increased pressure on operators of such plants to achieve near zero emission of contaminants and to reduce CO2 emission.
The art teaches various processes and technologies designed to reduce the emission of contaminants from combustion gases. Baghouses, electrostatic precipitators and wet scrubbers are typically used to capture particulate matter, various chemical processes are used to reduce sulfur oxides, HCl and HF emissions, combustion modifications and NOx reduction processes are used to reduce NOx emission and processes are being developed to capture mercury and other trace elements from combustion gas.
Significant progress has been made in the last 20-30 years and plants today are a lot cleaner and safer to the environment than in the past. However, there are growing indications that even small concentration of particulate matter and especially the very fine, less than 2.5 micron size particles (PM2.5), sulfur oxides, acid mist and mercury are harmful to human health and need to be controlled.
Controlling the residual emission is still a challenge and with existing technologies the cost of capturing the last few percents of harmful contaminants is very high.
In addition, in the last few years, there is a growing concern related to the accumulation of CO2, a greenhouse gas, in the atmosphere. The accelerated increase of CO2 concentration in the atmosphere is attributed to the growing use of fuels, such as coal, oil and gas, which release billions of tons of CO2 to the atmosphere every year.
Reduction in CO2 emission can be achieved by improving efficiency of energy utilization, by switching to lower carbon concentration fuels and by using alternative, CO2 neutral, energy sources. However, short of a major breakthrough in energy technology, CO2 emitting fuels will continue to be the main source of energy in the foreseeable future. Consequently, a low cost low energy consuming process for capturing and sequestering CO2 is needed to reverse the trend of global warming.
State of the art technologies for capturing CO2 are not suitable for operation with dirty, low pressure, low CO2 concentration, and oxygen containing combustion gases. Available commercial technologies for CO2 capture are energy intensive and high cost. If applied they would impose a heavy toll on the cost of energy utilization.
An applicable process currently available for post combustion CO2 capture is the amine process using Mono-Ethanol-Amine (MEA) or similar amines to react with CO2. The MEA process is capable of achieving high capture efficiency and of generating a concentrated CO2 stream for sequestration. However, the process has several drawbacks including:                The MEA reagent is expensive and degrades in oxygen and CO2 environment.        The MEA is corrosive and can be used only in a relatively diluted form.        The reaction of MEA with CO2 is highly exothermic.        Regeneration is energy intensive.        The process is a large consumer of heat and auxiliary power.        
The cost of the amine process and system is very high and the net power output of a power plant equipped with amine system to capture CO2 is greatly reduced.
To achieve clean burning of fuels with near zero emission, including the emission of CO2, there is a need for a low cost low energy process that:                Captures residual contaminants        Captures CO2 and releases it in a concentrated and high pressure form for sequestration.        
Accordingly, it would be considered an advance in the art to develop new systems and methods to overcome the current problems and shortcomings.